1. Field of the Invention
The present invention relates to a file management method for maintaining correspondence between a content file stored on a recording medium and an associated metadata file, a content recording/playback apparatus that implements this file management method, and a content recording program on which this file management method is recorded.
2. Description of the Related Art
Demand continues to grow for digital content distribution services that employ communications and broadcasting.
For example, a newspaper article distribution service has been conceived of whereby newspaper articles are downloaded each morning to a mobile phone and recorded onto a recording medium connected to that mobile phone, and an article can be read when wished by connecting that recording medium to another device such as a television set, portable display, portable personal organizer, or the like.
Also, an electronic book service has been conceived of whereby a novel is divided into chapters, and charging/downloading is performed chapter by chapter.
(Storage Package by Package)
As a concrete example of a newspaper article distribution service, a method can be considered whereby newspaper articles are written as HTML format files, and one day's worth of HTML files and image files or audio files accompanying those HTML files are distributed as a single package. With a service that distributes related contents as a single package in this way, a directory is generally created package by package for distributed content, and is recorded on a recording medium.
(Storage Service by Service)
Also, the capacity of recording media for downloading content is increasing at a rapid pace, and it has become possible for a large number of distribution services to be received on a single recording medium.
In this case, distributed content from a plurality of services coexists on a single recording medium, and generally a directory is created for each service on the recording medium and distributed content is recorded under the directory for the corresponding service.
(Provision of Metadata)
Moreover, in a content distribution service, information generally called metadata, comprising content related bibliographic matter, management information, attribute information, and so forth, is also distributed apart from the content, and recorded on the recording medium. In an apparatus that actually plays back/displays content, it is possible to perform operations other than playback/display, such as content searching or categorizing and organizing, by using the metadata accompanying that content.
(Metadata Recording Methods)
There are two methods for recording this kind of metadata on a recording medium: the case where the interior of a content file is constructed and metadata is also recorded by being stored in the same file as a part thereof, and the case where a metadata file is created separately from the content file, and metadata is recorded in individual files.
In an apparatus that receives content distribution, there are cases where original file names are assigned to a distributed content file and metadata file in order to enable efficient content recording and playback by means of simple processing.
For this reason, with the method, of the conventional metadata recording methods, whereby content and metadata are recorded in separate files, if, when a distributed content file and its metadata file are recorded on a recording medium of a receiving apparatus, original file names are assigned to these files on the receiving side, it becomes impossible to interpret the correspondence between them by means of the distribution-time file names.
On the other hand, with the method whereby metadata is recorded as part of a content file, the above problem does not occur, but metadata corresponds only to an individual content file, and it is difficult to write various kinds of metadata—such as metadata relating to a collection of a plurality of content files, metadata relating to an entire package, and metadata relating to an entire service—in a flexible manner.
Also, when performing processing using only metadata, such as searching, categorizing, listing, and so forth, it is necessary to acquire the contents of each content file, leading to problems in terms of processing efficiency.